For example, in a process of forming a capacitor of a DRAM (Dynamic Random Access Memory), it has been studied to form a comparatively deep recess in a SiO2 (silicon oxide) film. To this end, it is required to laminate a mask film having high etching selectivity to the SiO2 film on the SiO2 film. That is to say, there is a demand for forming a mask film having a high etching resistance on the SiO2 film when etching the SiO2 film.
It has been studied to form a W film as the mask film. This W film can be formed, for example, by supplying a process gas to a silicon film and substituting silicon with W. However, the W film thus formed has low adhesion to the SiO2 film. Thus, if the W film is directly laminated on the SiO2 film, the W film may be peeled off. If the W film peels off in this way, the W film does not function as a mask film. This may collapse a pattern shape. A technique is known for forming a W film to suppress such peeling. However, there is a demand for a technique that more reliably suppresses the peeling of the W film.